4,4'-thiobis(2,6-dialkyl)phenols are known compounds useful in various areas. For example, 4,4'-thiobis(2,6-di-t-butyl)phenol is a well known antioxidant and an effective synergist for other antioxidants. It is known from U.S. Pat. No. 3,835,196 to prepare compounds of this type by reacting 2,6-di-t butylphenol with an excess of sulfur in a solvent under basic conditions. This patent indicates that the solvent can be any solvent which would not react with the basic materials of the final product. Alcohols such as methanol, ethanol and ethylene glycol as well as solvents such as pyridine, dimethylformamide and dimethyl acetamide are indicated as preferred. Mixtures of these solvents in water in any proportions are indicated for use. In the specific example in this patent, the solvent was a 95% ethanol solution in water.
The present invention provides an improved solvent system for production of desired and preferred products of this type in high yields and high purity.